Sealing and testing of tubes by hydraulic or pneumatic means



Dec. 18, 1951 c. w. MUSSER 2,578,728

SEALING AND TESTING OF TUBES BY HYDRAULIC PNEUMATIC MEANS Filed March 18, 1949 2 SHEETS-SHEET 1 I3 z I 55 56 27 2/ 2a FIG. I. /9 9 f-Z H 34- 3 4a 37 as 53 3s EL 5 /9 U 56w y I i% 27 Q 3 5/ I i g INVENTOR.

I c. WALTON MUSSER.

FIG. 4.

ATTORNEYS Dec. 18, 1951 c. w. MUSSER 2,578,728

SEALING AND TESTING OF TUBES BY HYDRAULIC PNEUMATIC MEANS Filed March 18, 1949 2 SHEETSSHEET 2 FIG; 5.

INVENTOR.

c. WALTON MUSSER.

ATTOR N EYS.

Patented Dec. 18, 1951 UNITED STATES PATEN OFFICE SEALING AND TESTING. on TUBES BY HDBAULIG MA IC EA (Granted under the act of March 3, 1883, as "amended April 30, 1928; 370 0. G. 757) 7 Claims.

'The invention described in the specification d. claims may e, man iae re nd. u e by o for the Government tor governmental purposes without the payment to me at any royalty thereon.

My invention relates broadly to scaling and to hydraulic or pneumatic testing of hollow 'objects having one or more openings thereinto; nd. wh n n e sa y str t heie q has panama ref ren 'e o he s a in a Sub eiue i t s in 'o tube to is??? thei resi t" encid a burst/19g ress arc ed om With n- For illustrative purposes only, and in no way im o e t th a lica ion. f IeY lWem ti this disclosure i l ertain. o a Pie e Qt m ta ubi op n a oenq e mis- The tube. t b s a e u n m u ue iurent ve'meaas e provid n for he su a en estes of its resistance-to a bursting p essure applied by a force pump 13 and transmitted within the tube by a h d ul ed u QIlQ I O e t f m ent on s to prov de in proved means for quickly and effectively seal ing a tube by making use of the pressure employed to test the tubes resistance to'bursting.

her object is rov d a means o testin tubes which gives a more accurate; reliable in; dication of the actual physical p operties oi the tube.

A further object is to provide a means of test: i t b whi h l m nate he lo g d nal m.- pressive stress heretofore used in sealing the tube to be tested.

A still further object is to provide a means of reducing the amount of time required for each t st b l m n n the neces t Qf um in the testing m ium hack. t rts atd eels out Q the tube to be tested.

Yet another ob e t s to provide a of edu ing h vo me f hydrau is test ng med um. required for each test.

T e rego n and e h r ob t of ventive method'and apparatus will become apparent from an inspection of the following specification and accompanying drawings wherein;

1 is a d ew Partly se ti n or m unique invention showing some f the main elements thereof in the ""closed position, ready for the test.

Fig. 2 is a longitudinal section taken along line 2-2 of Fig. 1.

Fig. 3 is a'transyerse section taken along line 3-3of Fig. 2.

Fig. 4 is a longitudinal section, similar to Fig.

2 and showing how my inventioncan be inodlfled so as to further reduce the amount 0t time and the volume of fluid required for each test.

Fig. 5 is ascheinatic representation ofmyinventicn including not only the tube testing device proper but also a reservoir 'for the testing fluid and a pumping system for injecting and withdrawing the fluid from the tube.

Fig. 1 my invention is seen essentially to consist or a hollow cylindrical" test; chamber It which is securely mounted in a circular lug H protruding from a rigidly fiiied'bas'e I2. Integrally attached and leading from the inside of the test chamber Hi to a force pump (3 or pump reservoir i4 is one of a plurality of overflow fittings t3 and attached pipe M. The upper,

open end ii of test'chamb'ei' I ii is capped by a reciprocallysliding cover it having lug IT especially recessed for sliding contact with the upper end '55 ct test chamber It. A lower tube "supporting and sealing means [8 is mounted essentially concentric to the test chamber l0 inthe fixed base 12 by means of threads 19 and nut 2!] en lower stem 21. An upper tube supporting and sealing means 32 is similarly mounted in the sliding'cover 16 by means or, threads 23, washer 2c; and nut 25 on upper stem 26. Resting between the upper and lower tube supporting and sealing members 22 and I8 is the metal tubing 27? which is to be hydraulically tested'for resistance to a burstin pressure.

interposed between the upper tube supporting and sealing member 22 and the reciprocally sliding cover It is an adapter 2 8'which is s'lidably mounted on stem 25. By using various adapters, it is possible to accommodate fortsting difierent tubes having like inside diameter but different lengths. 4 v Mounted atop stem to are T fitting 2%, pressure re is gauge 30, a d l ed r m re 31 ellowed by flekible hose 32 which leads any fluid ot shown) bled 'throughthe valve back to a pump or pump reservoir '14. More in formation concerning theseparts will be disclosed later. '7 In my novel apparatus, hollow lower stem 2! is connected to the outlet of aforce pump 13 permitting the hydraulic testing medium (not shown) to be injected inside the tube'Z'I tQ b e tested Conversely, the hollow upper stem 26 provides a means, which leads \ba ckto the foroe pump it or the pump reservoir Mf of venting the apparatus. The more detailed structure of my unique means of sealing and testing tube 2! is clearly shown closed and ready for opration 2 There it can be seen that hollow cylindrical test chamber I is threadedly attached as indicated at 33 to lug II of fixed base I2. Located near the upper open end I of test chamber I0 is shown one of a number of overflow holes 34, communicating with fitting I3 and pipe I4. The upper open end I5 of test chamber I0 is shown slidably accommodated in the recess of lug I1 in reciprocally sliding cover I6.

Essentially concentric to the hollow cylindrical test chamber Ii), fixed base I2 contains an opening 36 to slidably accommodate lower stem 2| and a larger threaded opening to receive packing 31 and packing retainer 38. The retainer 38 has a threaded body portion 39, an expanded head portion 4|], and a central opening therethrough which permits the retainer to be fitted onto lower stem 2|.

The lower tube supporting and sealing means I8, located essentially concentrically within the hollow cylindrical test chamber I0, consists of a plug member 4| having a cylindrical portion 42 of slightly less diameter than the inside of the tube 21 to be tested, and a, truncated conical nose portion 43. Extending from the end of the cylindrical portion 42 of plug member 4|, away from the truncated portion 43, are a neck portion 44, a threaded shank portion 45 and the stem portion 2|.

Neck portion 44 accommodates a resilient sealing element 46 having a convenient central opening and an outside diameter, when free of stress, slightly less than the inside diameter of the tube 21 to be tested. Neck portion 44, in addition,

slidably fits into a central opening in a back-up plate 41 whose outside diameter is also slightly less than the inside diameter of the tube 21. A plurality of posts 48 having a portion of reduced diameter 49 and a shoulder 56 are securely pressed up to the shoulder 50 into convenient openings in the back-up plate 41.

By design, the total surface area of the truncated conical nose portion 43 is greater than the face area of the sealing element 46 (i. e.

. ing and sealing unit then consists of plug member the area of the surface which contacts the base of nose nortion 43) by a certain amount in order to accomplish one of the main features of my invention as will later be revealed.

A cuplike tube supporting member 5|, having a beveled mouth recess to slidably accommodate the outside diameter of the tube 21 to be tested, is secured to the shank 45 of plug member 4| by means of the threads of each member and is provided with convenient openings through which posts 48 pass.

As seen from the Fig. 2 relationships, the length of the neck portion 44 is substantially greater than the combined thickness of the unstressed sealing element 46, and the back-up plate 41 in order to provide an appreciable space 52 between the back-up plate and the bottom of the tube accommodating recess. In addition, the length i of the posts 48 below the shoulder 50 is greater 4|, resilient sealing element 46, back-up plate 41, posts 48, and cuplike member 5|, and is held in place in the fixed base I2 by means of threads I9 and nut 20 on stem 2|. Nut 20 is turned enough just to avoid stressing the sealing element 46. It will be noted from Fig. 2 that posts 48 rests on the fixed base I2 at the bottom of the test chamber recess.

It will be noted from the drawings that the upper tube supporting and sealing means 22 is of a construction identical with the lower tube supporting and sealing means 4|. However, since the upper tube supporting and sealing unit 22 moves with the cover I6, while the lower tube supporting and sealing unit I8 remains stationary in the fixed base I2, and since there is a slight difference in the mounting of the unit, confusion will hereinafter be avoided by independently referring to the various parts of the upper tube supporting and sealing unit 22; the following reference characters will, therefore, be used: upper plug member 56 having cylindrical portion 51, truncated conical nose portion 58, neck portion 59, threaded shank portion 60, and stem portion 26. Neck portion 59 accommodates resilient sealing element BI and back-up plate 62; backup plate 62 contans posts 63 having a shoulder 64 and a portion of reduced diameter (not shown), and cup-like tube supporting and sealing member 65. The upper plug member 56 has a central opening 66 and lateral openings 61.

All statements made about the various parts of the lower tube supporting and sealing means will apply to the corresponding parts of the upper tube supporting and sealing means with the ex ception that central opening 66 and lateral openings 61 provide a means of venting the apparatus. Posts 63 rest in light contact with the adapter 28 leaving the space 1| therebetween, and the upper tube supporting and sealing unit 22 is attached to cover I6 by means of upper stem 26 ex tending through an opening in adapter 28, and secured to the cover by means of threads 23, washer 24, and nut 25. The nut 25 is turned Enough to just avoid stressing the sealing element Figs. 12 described thus far refer to my invention in the closed position ready for testing the tube 21, although the hydraulic medium used is not shown. In describing the practice of my invention it will be expedient to commence with the apparatus in the open position, and to assume that tube 21 has not yet been positioned within the test chamber I6.

As can easily be construed from the drawings and description thus far presented, when the apparatus is in the open position the cover I6, with its appended adapter 28, upper tube supporting and sealing unit 22 and other parts, has been axially separated from open end I5 of the test chamber II] by automatic means (not shown). The amount of separation will depend upon the length of the tube 21 to be tested and need be only sufficient to provide space for insertion of the tube within the test chamber I0. Bleeder valve 3| has been automatically opened (by means not shown). The lower tube supporting and sealing unit I8 remains attached to the fixed base I2. 7

With the apparatus in the open position, tube 21 is introduced through the open end I5 of test chamber I0 and is placed into the lower cup-like tube support member 5|. By automatic means not shown) reciprocally sliding cover I6,

5. with its attached parts,is returnc'd'to its Fig. 1 position causing both ends ortube 21 to beinitially sealedin the following manner.

Cover l 8- is-urged towardthe fixed base l2 with a certain predetermined force and then looked in this position (by means not shown). A simple illustration of this would be if cover It were screwed unto test chamber It with a predetermined torque. That pressure is transmitted. through adapter 28, posts 63, back-up plate 52, resilient sealing element plug member 5.5, cup-like member 65, and tube 27, to the lower cup-like member 5!. At this lower end the pressure urging the cover It toward the base 12 is transmitted through lower cup-like member 51, plug member ll, resilient sealing element 5.6, back-up. plate 41, and posts 48 to the fixedbase [2. In consequence of this pressure the upper and lower sealing elements, BI and 46 respectively, are compressed between their respective adjoining plugs 56 and 4| and back-up plates 52 and 41, and are caused to press radially outward against the inner wall of the tube 21, this causing initial sealing. Cup-like members 51 and 6.5 meanwhile prevent any distortion of the tube 21.

With bleeder valve 3! still open, a hydraulic pump 63 is caused to inject the testing medium (not shown) into the inside of the tube through the central and lateral openings 54 and 55. respecti-vely. As the level of the fluid rises, air within the tube is vented off by means of lateral openings 5-! which communicate with the central opening -66, and escape past the bleeder valve 31.

When the level of the hydraulic testingmedium reaches the bleeder valve 3!, all air within the tube has been displaced and the bleeder valve is then closed, manually or automatically as desired. At this point, pressure begins to build up within the tube 2'1, the amount of pressure registering on gauge 30.

As the pressure within tube 21 increases, it tends to move upper and lower plug members 55 and ill apart. This results in a further compression of thesealing elements 5! and 46 causing them to contact the inside Wall of the tube 21 more forcefully. Therefore, as the test pres sure increases, the sealing pressure of the elements 6! and 46 also increases because of the fact that, since the surface area of each nose portion (58 and 43, respectively) exceeds the face area occupied by each sealing element, the unit pressure on the sealing elements is greater than the unit test pressure. The elements BI and 4B are therefore self-sealing.

As the pressure within the tube 21 increases it also tends to cause upper and lower cup-like members 65 and 5| to move apart in the corresponding spaces H and 53 provided therefor, thus relieving the initial compressive stress placed upon the tube by the action of cover it. The test will then be conducted without any appreciable longitudinal compressive stress which, if present, would complicate the analysis of the bursting strength.

When the desired test pressure, as registered on gauge 30, is reached, the pressure is stabilized (by means not shown) for the required amount of time. If the tube 2'! being tested sustains the test pressure for the predetermined length of time, the tube is assumed to have sulficient resistance against bursting causable by pressure. If the wall of the tube ruptures or deforms under the test pressure, of course the tube will be rejected as not having sufiicient resistance to the bursting pressure.

'Ineither'caseythe isccmplete and. th tub mustthen be removed from the test chamber I ll. To do this, :the test pressure exerted by a force pump. 13. is removed, but the hydr ulic t i medium is-permitted to remain within the tube 2-]. =Bleed'er valve 3|, is automatically opened (by means not shown) and cover 16 carrying the attached adapter 28- and upper tube supporting and sealing unit '22 is axially removed from atop the testchamber ill (by means not shown) a sumcient amountto allow the tube 21 to be extracted from the test chamber Ill.

As tube 2"! is extracted from test chamber (0 the hydraulic testing fluid (not shown) within tube '21" is permitted to run into the surrounding test chamber. The capacity of the test chamber it is determined bythe location of the overflow holes'34 (one of which isjshown in Fig. 2) which are so located that, when the next tube to be tested is positioned, it will already be verysubstantially, if not completely, filled with the hydraulic testing medium and it will only be necessary for the force'pump 13 to apply the test pressure or to deliver a very small additional quantity of the testing medium.

An alternative to allowing the test chamber it to fill gradually after each test is to pump the hydraulic medium (not shown) into the test chamber ill to the level of the overflow holes before the first test is made. Once the chamber I0 is capacitated, any excess will pass through holes 34, fittings I3 and pipes I4 back to the pump 13 or pump reservoir M.

It can be easily seen that not having to supply anything except, atthe most, very small quantities of testing. medium, would result in a great saving of time, especially where large voluminous tubes were to be t t d- .Prior to my invention, it was customary, in a. test. of. this kind, to seal the tube by app a longitudinal press re to s me p of Sealing a rangement placed over the ends of the tube. The ends of the tube-had to be reasonably perpendicular to the tubes axis and the sealing pressure used, which generally was, greatly in excess of the maximum available test pressure, resulted in the tubes being subjected to a longitudinal comprese sive stress. Moreover, this stress was present all during the test,

With my novel means, however, the tube 21 is not subjectedto a compressive stress durin the test, the tube ends need not be perpendic lar to the tubes axis, and the sealing pressure of the elements 5:! and. as against e tu e wa is ated solely bythe test: pressure In hydraulically testing objects having only one o ening into the interior. the inlet and vent openings 54 and fit'respectively can be conveniently located in the one requiredv plug member, preferably located at the highest possible point so as to avoid trapping air, which however would not influence the test pressure reading on gauge 30.

Another method of reducing the amount of time required for making each test and also of reducing the volume of hydraulic medium required is exemplified in Fig. 4. Here" the lower plug member 41a is recessed and threaded to reoeive the threaded end 68 of a mandrel 69. The upper plug member Elia-is similarly recessed to slidably accommodate the oppositcend ill of the mandrel. The diameter and length of the mandrel B9 are such as substant ally to fill the in of the tube 21 to be tested. it is easily apparent 7. that a very great reduction in the volume of testing fluid required would result from the adaption of this modification, and that a great saving of time and energy would consequently follow.

From the foregoing it will be seen that I have provided an improved means for quickly and effectively sealing a tube by making use of the pressure employed to test the tubes resistance to bursting; that I have provided a means of testing tubes which gives a more accurate, reliable indication of the actual physical properties of the tube; that I have provided a means of testing tubes which eliminates the longitudinal compressive stress heretofore used in sealing the tube to be tested; that I have provided a means of reducing the amount of time required for each test by eliminating the necessity of pumping the testing medium back and forth into and out of the tube to be tested; and that I have provided a means of reducing the volume of hydraulic medium required for each test.

With possible minor changes that will not depart from the spirit and intent of my invention, the means of sealing and testing of tubes here discussed can be used to seal and test practically any type of hollow object. In addition, an alternative technique to the hydraulic sealing and testing procedure set forth above will be to employ the apparatus for pneumatically sealing and testing tubes. My inventive means are therefore extensive in their adaption, and are not to be restricted to the specific form here disclosed by way of illustration.

I claim:

1. In apparatus of the character described, the combination of a tank open at one end, a fluidinlet member extending through the closed tank end, a reservoir for containing a hydraulic testing fluid, a pump connected between said reservoir and said fluid-inlet member, an overflow duct leading from within the tank to said reservoir, a first cup-shaped tube supporting means secured for limited longitudinal movement within said tank adjacent the tanks closed end, a first plug filling one end of the tube to be tested and comprised of a nose portion backed up by a resilient sealing member and a non-yieldable back-up plate, first rigid means forspacing said first plugs back-up plate from said tanks closed end, a cover secured to said tanks open end, a second cup-shaped tube supporting means secured to said cover for limited longitudinal movement with respect thereto, a second plug filling the end of the tube to be tested opposite to that filled by said first plug and comprised of a nose portion backed up by a resilient sealing member and a non-yieldable back-up plate, second rigid means for spacing said second plug s back-up plate from said cover whereby the pressure within the tube to be tested can be increased to cause the resilient sealing members to seal both tube ends and also move said first and second tube supporting means free of the tube ends so as to relieve them of any external compressive stress during the test.

2. In the apparatus of claim 1, the first plug having a mandrel threadedly secured thereto for extending into the tube being tested, whereby to occupy a considerable volume of the tubes interior and thereby to diminish the volume of testing fluid necessary to fill the tube in transmitting a testing pressure to the tubes sidewalls.

3. In the apparatus of claim 1, a mandrel positioned in the tube being tested, whereby to occupy a considerable volume of the tubes interior and thereby to diminish the volume of testing fluid necessary to fill the tube in transmitting a testing pressure to the tubes sidewalls.

4. In the apparatus of claim 1, the first plug having a mandrel threadedly secured at one end thereto for extending into the tube being tested, and the second plug having a recess for accommodating the free end of said mandrel, whereby the mandrel is supported in a substantially rigid manner within the tube being tested thus occupying a portion of the tubes internal volume and thereby diminishing the volume of testing fluid necessary to fill the tube in transmitting a testing pressure to the tubes sidewalls.

5. In apparatus for sealing and hydraulically testing the resistance of tubes and the like to internally applied pressure, the combination of first and second cup-shaped means for snugly encircling and supporting the ends of the tube being tested but capable of divergent longitudinal movement therefrom during the testing process, first and second plugs filling the respective tube ends, first and second resilient tube-sealing means each backing up the corresponding one of said plugs on the sides facing the respective tube ends, unyielding first and second stress-resisting means each backing up the corresponding one of said resilient sealing means, unyielding first and second fixtures respectively supporting said stressresisting means in position to prevent longitudinal movement of the sealing means in the direction of the respective supporting fixtures, a pump, fluid inlet means leading from said pump through said first tube supporting means and said first plug into the tube being tested, air venting means leading from the tubes interior through said second plug and said second tube supporting means, a bleeder valve attached to said air venting means, and a pressure gauge connected to said air venting means before said bleeder valve, whereby the pressure within the tube being tested can be increased so as to compress said first and second resilient means and force them radially against the tubes interior walls and simultaneously to diverge the said first and second tube supporting means free of contact with the tube ends 6. In apparatus for sealing and hydraulically testing the resistance of tubes and the like to internally applied bursting pressure, the combination of a base, a test chamber secured at one end in fluid-tight relationship to said base, fluid-conducting means having one end extending into the chamber through a mating opening in the latters closed end, a first tube supporting means mounted adjacent said base for limited axial movement relative to said chamber, a first plug having a cylindrical cross section dimensioned .so as substantially to fill the first end of the tube being tested, a first circular resilient sealing member whose normal diameter substantially equals that of said first plug and which is mounted adjacent the end of said plug nearest said base, first stress resisting means fixedly extending between said base and said first sealing member, a removable cover for closing the end of said chamber opposite to said base, a second tube supporting means mounted adjacent said cover for limited axial movement relative to said chamber, a second plug having a cylindrical cross section dimensioned so as substantially to fill the second end of the tube being tested, a second circular resilient sealing member whose normal diameter substantially equals that of said second plug and which is mounted adjacent the end of said plug nearest said cover, and second stress resisting means fixedly extending between said cover and said second sealing member, whereby said first and second tube supporting means secure the ends of the tube while the inside pressure thereof is being built up by admission of fluid thereinto so as to compress said sealing members into fluid-tight relationship with said tubes inner wall, but as the proper tube testing pressure is approached said tube supporting means are diverged from the tube ends so as to relieve the tube from any longitudinal compressive stress during the actual tube-testing operation.

'7. In apparatus of the character described, the combination of a tube-testing chamber having one end closed substantially fluid-tight but open at its other end, fluid-conducting means having one end extending into the chamber through a mating opening in the latters closed end, a reservoir for containing a testing fluid, a pump connected to said reservoir and to said fluid-conducting means for pumping the testing fluid from the reservoir into the chamber, an overflow duct connecting at one end with an opening in the chambers sidewall and at the other end emptying into said reservoir, a first tube supporting means mounted adjacent the chambers closed end for limited axial movement relative to said chamber, a first plug having a cylindrical cross section dimensioned so as substantially to fill the first end of the tube being tested, a first circular resilient sealing member whose normal diameter substantially equals that of said first plug and which is mounted adjacent the end of said plug nearest the first end of said tube, first stress resisting means fixedly extending between said base and said first sealing member, a removable cover for closing the end of said chamber opposite to said base, a second tube supporting means adjacent said cover for limited axial movement relative to said chamber, a second plug having a cylindrical cross section dimensioned so as substantially to fill the second end of the tube being tested, a second circular resilient sealing member whose normal diameter substantially equals that of said second plug and which is mounted adjacent the end of said plug nearest the second end of said tube, second stress resisting means fixedly extending between said cover and said second sealing member, an air-venting pipe extending through a mating opening in said cover and connecting with channels extending through said second plug, a bleeder valve attached to said pipe, and a pressure gauge connected to said pipe between the ccver and the bleeder valve, whereby said first and second tube supporting means secure the ends of the tube while the inside pressure thereof is being built up by admission of hydraulic fiuid thereinto so as to compress said sealing members into fluid tight relationship with said tubes inner wall but as the proper tube testing pressure is app :ached said tube supporting means are diverged from the tube ends so as to relieve the tube from any longitudinal compressive stress during the actual tube-testing operation.

CLARENCE WALTON MUSSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,118,478 Dixon Nov. 24, 1914 1,734,805 Hawthorne Nov. 5, 1929 1,841,974 Naylor Jan. 19, 1932 2,445,87 6 Fullerton July 27, 1948 FOREIGN PATENTS Number Country Date 551,566 Great Britain Mar. 1, 1943 

